This invention relates to an improvement in the nickel-catalyzed hydrogenation of phenol to cyclohexanol by maintaining hydrogen atmosphere throughout the process, including the final phase, separation of catalyst.
The manufacture of cyclohexanol by hydrogenation of phenol with nickel catalyst is known in U.S. Pat. No. 3,998,884 and particularly U.S. Pat. No. 2,794,056, both hereby incorporated by reference, in toto. In this patent application, by "hydrogen atmosphere" is meant pure hydrogen or mixtures of hydrogen with other gases so long as hydrogen is present in an amount over 10 percent by volume at 250 psig (1.72.times.10.sup.6 pascals) up to over 25 percent at atmospheric pressure. For example, a typical hydrogen atmosphere would be 75 percent H.sub.2 and 25 percent N.sub.2 at atmospheric pressure.